Cement Body Research Articles

Characteristics of Hydrated Alite in Hardened Cement Body

The hydration characteristics of cement in hardened cement paste, mortar and concrete were investigated and discussed from the stand points of hydration degree, pore structure, composition and structure of hydrates. In hardened cement pastes, area proportion of a darkest part in the back scattered electron image of its polished surface closely correlated with the volume of pores more than 50nm in diameter. In the cases of hardened mortar and concrete, however, the abovementioned correlation was not so good, since they had additional porous structures called a transitional zone, which was composed of Ca(OH)2 precipitated around aggregate grains. Dense C-S-H layer in hardened mortar and concrete formed around unhydrated alite was thicker and its average Ca/Si molar ratio was by 0.2 lower than that of hardened cement paste. This phenomenon is considered to be caused by the low Ca ion concentration in a liquid phase due to the presence of an aggregate, by the high degree of hydration of cement and by local precipitation of Ca(OH)2 around an aggregate in hardened mortar and concrete.

The release of gentamicin after total hip replacement using low or high viscosity bone cement

Low viscosity bone cement is expected to give improved long term fixation of prosthetic components by increased intrusion into cancellous bone. Fixation is more difficult to achieve after revision for infection because of the inferior quality of the bone. We have compared the amount of gentamicin released from high viscosity and low viscosity bone cements in 41 patients undergoing total hip replacement. The concentration of gentamicin in serum and the wound secretion, and the amount recovered from the urine, was about three times higher for low viscosity cement. A possible explanation for this is an increase in surface area of the cement body because of improved intrusion of cement into bone. The improved mechanical fixation and the high concentration of gentamicin of the bone cement interface favours the use of low viscosity cement, especially in revision for deep infection.

Fine structure of the spermatophores and their ejaculated forms, sperm reservoirs, of the Japanese common squid, Todarodes pacificus.

Spermatophores in a squid, Todarodes pacificus, were observed by light and electron microscopy and were further analyzed by X-ray microanalysis (XMA) of frozen thin sections. Each spermatophore consists of a sperm mass, a cement body, an ejaculatory apparatus, and some fluid materials, all of which are covered by an outer tunic. The outer tunic consists of about 20 membranous layers, each containing straight, parallel microgrooves. Each layer's microgroove pattern is roughly in an orthogonal arrangement with respect to the next layer's pattern. The sperm mass, which is the only cellular component, consists of a sperm rope which is coiled more than 500 times. Most of the spermatozoa in the rope are arranged regularly and are enveloped in materials which are well-stained by Alcian blue. The cement body is located between the sperm mass and ejaculatory apparatus and has a hard outer shell with an arrowhead-like structure, presumably for penetration into the tissue of the female. Calcium and phosphorus are present in the shell of the cement body, which also has an affinity for alizarin red. The ejaculatory apparatus consists of two tubes, designated as the inner tunic and the inner membrane. After the spermatophoric reaction, a sperm reservoir is formed at the anterior end of the extruded and inverted ejaculatory apparatus. The sperm reservoir, which encases the sperm mass, is composed of the cement body at the anterior end and the inner tunic of the ejaculatory apparatus at the posterior end.

Process for impregnating a concrete or cement body with a polymeric material: Mattus, A. J. and Spence, R. D. (Department of Energy, Washington DC, USA) US Pat 4 828 761 (9 May 1989)

Process for impregnating a concrete or cement body with a polymeric material: Mattus, A. J. and Spence, R. D. (Department of Energy, Washington DC, USA) US Pat 4 828 761 (9 May 1989)

Durability tests on polymer-cement mortar

Accelerated durability tests on several polymer-impregnated mortars have been studied in aqueous sulphuric acid (3:1 v/v) and hydrochloric acid (3:1 v/v) media. In addition to the reactivity of individual polymers and cement body in these corrosive environments, the cement-polymer interaction has been identified as an important factor which controls the durability properties of the composites.

Improvement in the properties of gypsum casts by polymer impregnation

It is known that porous solids such as Portland cement, concrete, and ceramic tile bodies can be strengthened by polymer impregnation. The solid material is infiltrated with a liquid monomer, which is then polymerized in situ. In the present investigation, it has been found that this process is effective for strengthening gypsum casts prepared from ordinary laboratory plaster. Impregnation with poly(methyl methacrylate) confers marked improvements in tensile and compressive strength and abrasion resistance. The process would be particularly applicable to the preservation of study casts for record purposes.

Male reproductive tract, spermatophores and spermatophoric reaction in the giant octopus of the North Pacific, Octopus dofleini martini.

The male reproductive tract of Octopus dofleini martini lies enclosed in the genital bag, inside the mantle cavity. It consists of the testis, vas deferens proximale, spermatophoric gland system I (seminal vesicle), spermatophoric gland system II (prostate), vas deferens distale, spermatophoric sac (Needham’s sac) and the terminal spermatophoric duct. The spermatozoa, which upon leaving the testis are as yet not encased, pass first into the vas deferens proximale, which in its gross appearance resembles the epididymis; they then traverse the two tubular spermatophoric gland systems I and II, where they become encased into the spermatophores. Subsequently the spermatophores pass through the vas deferens distale into the spindle-shaped spermatophoric sac, and from there they enter singly the terminal spermatophoric duct consisting of the diverticulum and terminal organ or ‘penis’. The slender cylindrical body of the spermatophore is about 1 m long and consists of two parts, approximately equal in length. The thicker ‘proximal’ ‘male-oriented’ portion, which emerges first from the orifice of the ‘penis’, contains the tightly coiled sperm rope suspended in a viscous and transparent fluid, the spermatophoric plasma; the thinner ‘distal’ ‘femaleoriented’ half of the spermatophore is taken up by the rod-shaped, hyaline core of the ejaculatory apparatus. In between is located the cement body, and the amber-coloured cement liquid. At the distal end of the spermatophore the outer coating forms a cap and a filamentous appendage, the cap-thread. Chemical analyses were performed on spermatozoa, spermatophoric plasma, cement liquid, outer tunic and the hyaline core of the ejaculatory apparatus, obtained from freshly recovered spermatophores. Glycogen was identified as a major constituent of spermatozoa. The extraordinarily high dry-weight content of spermatophoric plasma (nearly 30%) was shown to be largely due to bound amino sugar, carbohydrate, peptide and protein. A peptide separated from the spermatophoric plasma by ultrafiltration was found to be made up to a great extent of aspartic acid and serine. The outer tunic, a tough and elastic membrane, which envelops the body of the spermatophore, was shown to consist mostly of a protein which is rich in proline, lysine, aspartic acid and threonine. The mechanics of the spermatophoric reaction in vitro have been studied in spermatophores extracted manually from the male octopus and placed in sea-water. The complete spermatophoric reaction under such conditions lasted 1 to 2 h. During that interval the sperm rope gradually advanced a distance of about 1 m, from the proximal towards the distal end of the spermatophore. The terminal phase of this process involved an evagination of the ejaculatory apparatus, followed by a rapid movement of the sperm rope; as the sperm rope entered the end portion of the spermatophore, the latter ballooned out into an egg-shaped bladder. Among the factors which contribute to the formation of the spermatophoric bladder, the most important ones are (i) the elasticity of the membranes of the spermatophore, (ii) the extrusion, and subsequently evagination, of the ejaculatory apparatus, and (iii) the influx of sea-water into the spermatophore’s body which causes an approximately fivefold increase in the volume of spermatophoric plasma. Concomitantly with the uptake of sea-water, the dry weight of the spermatophorie plasma declines but the sodium chloride concentration increases. However, the osmolality of the spermatophoric plasma, as assessed by freezingpomt depression, is not altered during the spermatophoric reaction. Events at copulation, that is under conditions in vivo , closely resembled those observed in spermatophores undergoing a spermatophoric reaction in vitro . An interval of 2 to 3 h usually elapsed from the time when the male, using his hectocotylized arm, mserted mto the female the distal (female-oriented) end of a spermatophore, to the moment of the male's withdrawal. After accomplished copulation two spermatophores were usually found firmly lodged in the two oviducts. The sperm-free remnants of the spermatophore bodies dangled free from the orifices of the oviducts. Upon dissection of recently mated females the spermatophoric bladder was usually found within the oviduct, held firmly in position by the evaginated ejaculatory apparatus.

The brittle fracture of cemented bodies

The brittle fracture of cemented bodies

Effect of Gravel on Unconsolidated Sands

The important factors in any study of the screening of sand with a gravelenvelope, as applied to use in oil wells, are:gravel size upon sand migrationsand size and shapegravel size and shaperatio of gravel size tosand sizeflow velocityviscosity of the fluid. Perhaps the first extensive investigation of the function of gravel inscreening sand was performed by Coberly and Wagner,' from which the followingconclusion was drawn: "The diameter of the largest grains in a singleclassified sand suitable for gravel packing is approximately 13 times the grainsize at the ten-percentile analysis of the formation sample." This appliesto sands classified by Tyler screens and is for gravel grains of the maximumsize that could be used to form a stable bridge. Field practice has shown thatthe screening effect of a given gravel for a given sand apparently varies withthe flow velocity. 2 Also, it has been assumed by some operators that thethickness of the walls of the gravel envelope surrounding the well has littleeffect upon the screening process. It is thought by others that a narrowenvelope of gravel might form an ineffective screen. Thus the purposes of thiswork are:To investigate the effect of gravel-sand size ratio upon screening actionunder the condition of varying flow velocities.To investigate the effect upon screening action of varying the thickness ofthe gravel screen.To investigate sand migration in the gravel screen and the effect of flowvelocity and gravel size upon sand migration. Description of Apparatus In an attempt to reproduce field conditions for the purposes of thisinvestigation, a flow tube was constructed, according to the manner of Uren, torepresent a radial drainage segment of an oil sand. To arrive at the dimensions of the flow tube, a radial drainage segment ofrectangular cross section was assumed to define an area of 2 sq. in. on theface of a well 6 in. in diameter. From this the dimensions of the segment werecalculated out to a distance of 5 ft. from the face of the well. By computingcross-sectional areas at a number of sections along the rectangular segment andtransforming these areas into the circular form, a drainage cone was obtainedhaving everywhere the same cross-sectional area as the drainage element ofrectangular cross section. To construct the apparatus, two sections of pipe of 7 5/8 in. inside diameter, one 13 in. and the other 4 ft. long, were joined by a bolted flange. A mandrelhaving the dimensions of the drainage cone was centered in the pipe and a neatcement mixture was cast around it. A protective gasket was placed between thetwo sections of pipe so that the cement body could be separated at that point.When the mandrel was withdrawn a drainage cone was obtained A round slotted screen, which could be screwed up against the end of thedrainage cone, held the gravel in place. T.P. 1195